HAWQ-1062. Remove ASF incompatible Perl JSON module

* Remove JSON Perl Module (Artistic license) module (files and
  directory) from source tree.  The user wanting to run these Perl JSON
  module dependent scripts (tidycat.pl, calico.pl, caqluniqdef.pl) are
  instructed to download it from www.cpan.org if it is not found in dev
  environment.  Here is error message received if JSON Perl Module is
  not found:

    Fatal Error: The required package JSON is not installed -- please
    download it from www.cpan.org

  JSON Perl Module versions 2.27 through 2.90 are known to work.

* Update LICENSE file and remove licenses/LICENSE-json.txtfile.


Project: http://git-wip-us.apache.org/repos/asf/incubator-hawq/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-hawq/commit/17342b7f
Tree: http://git-wip-us.apache.org/repos/asf/incubator-hawq/tree/17342b7f
Diff: http://git-wip-us.apache.org/repos/asf/incubator-hawq/diff/17342b7f

Branch: refs/heads/master
Commit: 17342b7fe718c4f1363c54c2d52fe7837b531a36
Parents: 281014e
Author: Ed Espino <esp...@apache.org>
Authored: Wed Sep 21 00:07:26 2016 -0700
Committer: Ed Espino <esp...@apache.org>
Committed: Wed Sep 21 00:07:26 2016 -0700

----------------------------------------------------------------------
 LICENSE                                |    3 -
 licenses/LICENSE-json.txt              |  131 --
 src/include/catalog/JSON.pm            | 2223 ---------------------------
 src/include/catalog/JSON/PP.pm         | 2191 --------------------------
 src/include/catalog/JSON/PP/Boolean.pm |   26 -
 src/include/catalog/JSON/PP5005.pm     |  146 --
 src/include/catalog/JSON/PP56.pm       |  198 ---
 src/include/catalog/JSON/PP58.pm       |   93 --
 8 files changed, 5011 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-hawq/blob/17342b7f/LICENSE
----------------------------------------------------------------------
diff --git a/LICENSE b/LICENSE
index 62a4872..02e1967 100644
--- a/LICENSE
+++ b/LICENSE
@@ -383,9 +383,6 @@ Perl LICENSE
   license. See project link for details.  The text of each license is
   also included at licenses/LICENSE-[project].txt.
 
-     JSON 
-       src/include/catalog/JSON
-  
      plperl
        src/pl/plperl
       

http://git-wip-us.apache.org/repos/asf/incubator-hawq/blob/17342b7f/licenses/LICENSE-json.txt
----------------------------------------------------------------------
diff --git a/licenses/LICENSE-json.txt b/licenses/LICENSE-json.txt
deleted file mode 100644
index 71dd596..0000000
--- a/licenses/LICENSE-json.txt
+++ /dev/null
@@ -1,131 +0,0 @@
-Copyright 2007-2010 by Makamaka Hannyaharamitu
-
-The "Artistic License"
-
-Preamble
-
-The intent of this document is to state the conditions under which a
-Package may be copied, such that the Copyright Holder maintains some
-semblance of artistic control over the development of the package,
-while giving the users of the package the right to use and distribute
-the Package in a more-or-less customary fashion, plus the right to make
-reasonable modifications.
-
-Definitions:
-
-"Package" refers to the collection of files distributed by the
-Copyright Holder, and derivatives of that collection of files
-created through textual modification.
-
-"Standard Version" refers to such a Package if it has not been
-modified, or has been modified in accordance with the wishes
-of the Copyright Holder as specified below.
-
-"Copyright Holder" is whoever is named in the copyright or
-copyrights for the package.
-
-"You" is you, if you're thinking about copying or distributing
-this Package.
-
-"Reasonable copying fee" is whatever you can justify on the
-basis of media cost, duplication charges, time of people involved,
-and so on.  (You will not be required to justify it to the
-                 Copyright Holder, but only to the computing community at large
-                 as a market that must bear the fee.)
-
-"Freely Available" means that no fee is charged for the item
-itself, though there may be fees involved in handling the item.
-It also means that recipients of the item may redistribute it
-under the same conditions they received it.
-
-1. You may make and give away verbatim copies of the source form of the
-Standard Version of this Package without restriction, provided that you
-duplicate all of the original copyright notices and associated disclaimers.
-
-2. You may apply bug fixes, portability fixes and other modifications
-derived from the Public Domain or from the Copyright Holder.  A Package
-modified in such a way shall still be considered the Standard Version.
-
-3. You may otherwise modify your copy of this Package in any way, provided
-that you insert a prominent notice in each changed file stating how and
-when you changed that file, and provided that you do at least ONE of the
-following:
-
-a) place your modifications in the Public Domain or otherwise make them
-Freely Available, such as by posting said modifications to Usenet or
-an equivalent medium, or placing the modifications on a major archive
-site such as uunet.uu.net, or by allowing the Copyright Holder to include
-your modifications in the Standard Version of the Package.
-
-b) use the modified Package only within your corporation or organization.
-
-c) rename any non-standard executables so the names do not conflict
-with standard executables, which must also be provided, and provide
-a separate manual page for each non-standard executable that clearly
-documents how it differs from the Standard Version.
-
-d) make other distribution arrangements with the Copyright Holder.
-
-4. You may distribute the programs of this Package in object code or
-executable form, provided that you do at least ONE of the following:
-
-a) distribute a Standard Version of the executables and library files,
-together with instructions (in the manual page or equivalent) on where
-to get the Standard Version.
-
-b) accompany the distribution with the machine-readable source of
-the Package with your modifications.
-
-c) give non-standard executables non-standard names, and clearly
-document the differences in manual pages (or equivalent), together
-with instructions on where to get the Standard Version.
-
-d) make other distribution arrangements with the Copyright Holder.
-
-5. You may charge a reasonable copying fee for any distribution of this
-Package.  You may charge any fee you choose for support of this
-Package.  You may not charge a fee for this Package itself.  However,
-you may distribute this Package in aggregate with other (possibly
-commercial) programs as part of a larger (possibly commercial) software
-distribution provided that you do not advertise this Package as a
-product of your own.  You may embed this Package's interpreter within
-an executable of yours (by linking); this shall be construed as a mere
-form of aggregation, provided that the complete Standard Version of the
-interpreter is so embedded.
-
-6. The scripts and library files supplied as input to or produced as
-output from the programs of this Package do not automatically fall
-under the copyright of this Package, but belong to whoever generated
-them, and may be sold commercially, and may be aggregated with this
-Package.  If such scripts or library files are aggregated with this
-Package via the so-called "undump" or "unexec" methods of producing a
-binary executable image, then distribution of such an image shall
-neither be construed as a distribution of this Package nor shall it
-fall under the restrictions of Paragraphs 3 and 4, provided that you do
-not represent such an executable image as a Standard Version of this
-Package.
-
-7. C subroutines (or comparably compiled subroutines in other
-languages) supplied by you and linked into this Package in order to
-emulate subroutines and variables of the language defined by this
-Package shall not be considered part of this Package, but are the
-equivalent of input as in Paragraph 6, provided these subroutines do
-not change the language in any way that would cause it to fail the
-regression tests for the language.
-
-8. Aggregation of this Package with a commercial distribution is always
-permitted provided that the use of this Package is embedded; that is,
-when no overt attempt is made to make this Package's interfaces visible
-to the end user of the commercial distribution.  Such use shall not be
-construed as a distribution of this Package.
-
-9. The name of the Copyright Holder may not be used to endorse or promote
-products derived from this software without specific prior written permission.
-
-10. THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
-IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
-WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
-
-The End
-Contact GitHub API Training Shop Blog About
-© 2016 GitHub, Inc. Terms Privacy Security Status Help

http://git-wip-us.apache.org/repos/asf/incubator-hawq/blob/17342b7f/src/include/catalog/JSON.pm
----------------------------------------------------------------------
diff --git a/src/include/catalog/JSON.pm b/src/include/catalog/JSON.pm
deleted file mode 100644
index 661cb25..0000000
--- a/src/include/catalog/JSON.pm
+++ /dev/null
@@ -1,2223 +0,0 @@
-package JSON;
-
-
-use strict;
-use Carp ();
-use base qw(Exporter);
-@JSON::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json 
decode_json);
-
-BEGIN {
-    $JSON::VERSION = '2.27';
-    $JSON::DEBUG   = 0 unless (defined $JSON::DEBUG);
-}
-
-my $Module_XS  = 'JSON::XS';
-my $Module_PP  = 'JSON::PP';
-my $XS_Version = '2.27';
-
-
-# XS and PP common methods
-
-my @PublicMethods = qw/
-    ascii latin1 utf8 pretty indent space_before space_after relaxed canonical 
allow_nonref 
-    allow_blessed convert_blessed filter_json_object 
filter_json_single_key_object 
-    shrink max_depth max_size encode decode decode_prefix allow_unknown
-/;
-
-my @Properties = qw/
-    ascii latin1 utf8 indent space_before space_after relaxed canonical 
allow_nonref
-    allow_blessed convert_blessed shrink max_depth max_size allow_unknown
-/;
-
-my @XSOnlyMethods = qw//; # Currently nothing
-
-my @PPOnlyMethods = qw/
-    indent_length sort_by
-    allow_singlequote allow_bignum loose allow_barekey escape_slash 
as_nonblessed
-/; # JSON::PP specific
-
-
-# used in _load_xs and _load_pp ($INSTALL_ONLY is not used currently)
-my $_INSTALL_DONT_DIE  = 1; # When _load_xs fails to load XS, don't die.
-my $_INSTALL_ONLY      = 2; # Don't call _set_methods()
-my $_ALLOW_UNSUPPORTED = 0;
-my $_UNIV_CONV_BLESSED = 0;
-
-
-# Check the environment variable to decide worker module. 
-
-unless ($JSON::Backend) {
-    $JSON::DEBUG and  Carp::carp("Check used worker module...");
-
-    my $backend = exists $ENV{PERL_JSON_BACKEND} ? $ENV{PERL_JSON_BACKEND} : 1;
-
-    if ($backend eq '1' or $backend =~ /JSON::XS\s*,\s*JSON::PP/) {
-        _load_xs($_INSTALL_DONT_DIE) or _load_pp();
-    }
-    elsif ($backend eq '0' or $backend eq 'JSON::PP') {
-        _load_pp();
-    }
-    elsif ($backend eq '2' or $backend eq 'JSON::XS') {
-        _load_xs();
-    }
-    else {
-        Carp::croak "The value of environmental variable 'PERL_JSON_BACKEND' 
is invalid.";
-    }
-}
-
-
-sub import {
-    my $pkg = shift;
-    my @what_to_export;
-    my $no_export;
-
-    for my $tag (@_) {
-        if ($tag eq '-support_by_pp') {
-            if (!$_ALLOW_UNSUPPORTED++) {
-                JSON::Backend::XS
-                    ->support_by_pp(@PPOnlyMethods) if ($JSON::Backend eq 
$Module_XS);
-            }
-            next;
-        }
-        elsif ($tag eq '-no_export') {
-            $no_export++, next;
-        }
-        elsif ( $tag eq '-convert_blessed_universally' ) {
-            eval q|
-                require B;
-                *UNIVERSAL::TO_JSON = sub {
-                    my $b_obj = B::svref_2object( $_[0] );
-                    return    $b_obj->isa('B::HV') ? { %{ $_[0] } }
-                            : $b_obj->isa('B::AV') ? [ @{ $_[0] } ]
-                            : undef
-                            ;
-                }
-            | if ( !$_UNIV_CONV_BLESSED++ );
-            next;
-        }
-        push @what_to_export, $tag;
-    }
-
-    return if ($no_export);
-
-    __PACKAGE__->export_to_level(1, $pkg, @what_to_export);
-}
-
-
-# OBSOLETED
-
-sub jsonToObj {
-    my $alternative = 'from_json';
-    if (defined $_[0] and UNIVERSAL::isa($_[0], 'JSON')) {
-        shift @_; $alternative = 'decode';
-    }
-    Carp::carp "'jsonToObj' will be obsoleted. Please use '$alternative' 
instead.";
-    return JSON::from_json(@_);
-};
-
-sub objToJson {
-    my $alternative = 'to_json';
-    if (defined $_[0] and UNIVERSAL::isa($_[0], 'JSON')) {
-        shift @_; $alternative = 'encode';
-    }
-    Carp::carp "'objToJson' will be obsoleted. Please use '$alternative' 
instead.";
-    JSON::to_json(@_);
-};
-
-
-# INTERFACES
-
-sub to_json ($@) {
-    if ( ref($_[0]) eq 'JSON' or $_[0] eq 'JSON' ) {
-        Carp::croak "to_json should not be called as a method.";
-    }
-    my $json = new JSON;
-
-    if (@_ == 2 and ref $_[1] eq 'HASH') {
-        my $opt  = $_[1];
-        for my $method (keys %$opt) {
-            $json->$method( $opt->{$method} );
-        }
-    }
-
-    $json->encode($_[0]);
-}
-
-
-sub from_json ($@) {
-    if ( ref($_[0]) eq 'JSON' or $_[0] eq 'JSON' ) {
-        Carp::croak "from_json should not be called as a method.";
-    }
-    my $json = new JSON;
-
-    if (@_ == 2 and ref $_[1] eq 'HASH') {
-        my $opt  = $_[1];
-        for my $method (keys %$opt) {
-            $json->$method( $opt->{$method} );
-        }
-    }
-
-    return $json->decode( $_[0] );
-}
-
-
-sub true  { $JSON::true  }
-
-sub false { $JSON::false }
-
-sub null  { undef; }
-
-
-sub require_xs_version { $XS_Version; }
-
-sub backend {
-    my $proto = shift;
-    $JSON::Backend;
-}
-
-#*module = *backend;
-
-
-sub is_xs {
-    return $_[0]->module eq $Module_XS;
-}
-
-
-sub is_pp {
-    return $_[0]->module eq $Module_PP;
-}
-
-
-sub pureperl_only_methods { @PPOnlyMethods; }
-
-
-sub property {
-    my ($self, $name, $value) = @_;
-
-    if (@_ == 1) {
-        my %props;
-        for $name (@Properties) {
-            my $method = 'get_' . $name;
-            if ($name eq 'max_size') {
-                my $value = $self->$method();
-                $props{$name} = $value == 1 ? 0 : $value;
-                next;
-            }
-            $props{$name} = $self->$method();
-        }
-        return \%props;
-    }
-    elsif (@_ > 3) {
-        Carp::croak('property() can take only the option within 2 arguments.');
-    }
-    elsif (@_ == 2) {
-        if ( my $method = $self->can('get_' . $name) ) {
-            if ($name eq 'max_size') {
-                my $value = $self->$method();
-                return $value == 1 ? 0 : $value;
-            }
-            $self->$method();
-        }
-    }
-    else {
-        $self->$name($value);
-    }
-
-}
-
-
-
-# INTERNAL
-
-sub _load_xs {
-    my $opt = shift;
-
-    $JSON::DEBUG and Carp::carp "Load $Module_XS.";
-
-    # if called after install module, overload is disable.... why?
-    JSON::Boolean::_overrride_overload($Module_XS);
-    JSON::Boolean::_overrride_overload($Module_PP);
-
-    eval qq|
-        use $Module_XS $XS_Version ();
-    |;
-
-    if ($@) {
-        if (defined $opt and $opt & $_INSTALL_DONT_DIE) {
-            $JSON::DEBUG and Carp::carp "Can't load $Module_XS...($@)";
-            return 0;
-        }
-        Carp::croak $@;
-    }
-
-    unless (defined $opt and $opt & $_INSTALL_ONLY) {
-        _set_module( $JSON::Backend = $Module_XS );
-        my $data = join("", <DATA>); # this code is from Jcode 2.xx.
-        close(DATA);
-        eval $data;
-        JSON::Backend::XS->init;
-    }
-
-    return 1;
-};
-
-
-sub _load_pp {
-    my $opt = shift;
-
-    $JSON::DEBUG and Carp::carp "Load $Module_PP.";
-
-    # if called after install module, overload is disable.... why?
-    JSON::Boolean::_overrride_overload($Module_XS);
-    JSON::Boolean::_overrride_overload($Module_PP);
-
-    eval qq| require $Module_PP |;
-    if ($@) {
-        Carp::croak $@;
-    }
-
-    unless (defined $opt and $opt & $_INSTALL_ONLY) {
-        _set_module( $JSON::Backend = $Module_PP );
-        JSON::Backend::PP->init;
-    }
-};
-
-
-sub _set_module {
-    my $module = shift;
-
-    local $^W;
-    no strict qw(refs);
-
-    $JSON::true  = ${"$module\::true"};
-    $JSON::false = ${"$module\::false"};
-
-    push @JSON::ISA, $module;
-    push @{"$module\::Boolean::ISA"}, qw(JSON::Boolean);
-
-    *{"JSON::is_bool"} = \&{"$module\::is_bool"};
-
-    for my $method ($module eq $Module_XS ? @PPOnlyMethods : @XSOnlyMethods) {
-        *{"JSON::$method"} = sub {
-            Carp::carp("$method is not supported in $module.");
-            $_[0];
-        };
-    }
-
-    return 1;
-}
-
-
-
-#
-# JSON Boolean
-#
-
-package JSON::Boolean;
-
-my %Installed;
-
-sub _overrride_overload {
-    return if ($Installed{ $_[0] }++);
-
-    my $boolean = $_[0] . '::Boolean';
-
-    eval sprintf(q|
-        package %s;
-        use overload (
-            '""' => sub { ${$_[0]} == 1 ? 'true' : 'false' },
-            'eq' => sub {
-                my ($obj, $op) = ref ($_[0]) ? ($_[0], $_[1]) : ($_[1], $_[0]);
-                if ($op eq 'true' or $op eq 'false') {
-                    return "$obj" eq 'true' ? 'true' eq $op : 'false' eq $op;
-                }
-                else {
-                    return $obj ? 1 == $op : 0 == $op;
-                }
-            },
-        );
-    |, $boolean);
-
-    if ($@) { Carp::croak $@; }
-
-    return 1;
-}
-
-
-#
-# Helper classes for Backend Module (PP)
-#
-
-package JSON::Backend::PP;
-
-sub init {
-    local $^W;
-    no strict qw(refs);
-    *{"JSON::decode_json"} = \&{"JSON::PP::decode_json"};
-    *{"JSON::encode_json"} = \&{"JSON::PP::encode_json"};
-    *{"JSON::PP::is_xs"}  = sub { 0 };
-    *{"JSON::PP::is_pp"}  = sub { 1 };
-    return 1;
-}
-
-#
-# To save memory, the below lines are read only when XS backend is used.
-#
-
-package JSON;
-
-1;
-__DATA__
-
-
-#
-# Helper classes for Backend Module (XS)
-#
-
-package JSON::Backend::XS;
-
-use constant INDENT_LENGTH_FLAG => 15 << 12;
-
-use constant UNSUPPORTED_ENCODE_FLAG => {
-    ESCAPE_SLASH      => 0x00000010,
-    ALLOW_BIGNUM      => 0x00000020,
-    AS_NONBLESSED     => 0x00000040,
-    EXPANDED          => 0x10000000, # for developer's
-};
-
-use constant UNSUPPORTED_DECODE_FLAG => {
-    LOOSE             => 0x00000001,
-    ALLOW_BIGNUM      => 0x00000002,
-    ALLOW_BAREKEY     => 0x00000004,
-    ALLOW_SINGLEQUOTE => 0x00000008,
-    EXPANDED          => 0x20000000, # for developer's
-};
-
-
-sub init {
-    local $^W;
-    no strict qw(refs);
-    *{"JSON::decode_json"} = \&{"JSON::XS::decode_json"};
-    *{"JSON::encode_json"} = \&{"JSON::XS::encode_json"};
-    *{"JSON::XS::is_xs"}  = sub { 1 };
-    *{"JSON::XS::is_pp"}  = sub { 0 };
-    return 1;
-}
-
-
-sub support_by_pp {
-    my ($class, @methods) = @_;
-
-    local $^W;
-    no strict qw(refs);
-
-    my $JSON_XS_encode_orignal     = \&JSON::XS::encode;
-    my $JSON_XS_decode_orignal     = \&JSON::XS::decode;
-    my $JSON_XS_incr_parse_orignal = \&JSON::XS::incr_parse;
-
-    *JSON::XS::decode     = \&JSON::Backend::XS::Supportable::_decode;
-    *JSON::XS::encode     = \&JSON::Backend::XS::Supportable::_encode;
-    *JSON::XS::incr_parse = \&JSON::Backend::XS::Supportable::_incr_parse;
-
-    *{JSON::XS::_original_decode}     = $JSON_XS_decode_orignal;
-    *{JSON::XS::_original_encode}     = $JSON_XS_encode_orignal;
-    *{JSON::XS::_original_incr_parse} = $JSON_XS_incr_parse_orignal;
-
-    push @JSON::Backend::XS::Supportable::ISA, 'JSON';
-
-    my $pkg = 'JSON::Backend::XS::Supportable';
-
-    *{JSON::new} = sub {
-        my $proto = new JSON::XS; $$proto = 0;
-        bless  $proto, $pkg;
-    };
-
-
-    for my $method (@methods) {
-        my $flag = uc($method);
-        my $type |= (UNSUPPORTED_ENCODE_FLAG->{$flag} || 0);
-           $type |= (UNSUPPORTED_DECODE_FLAG->{$flag} || 0);
-
-        next unless($type);
-
-        $pkg->_make_unsupported_method($method => $type);
-    }
-
-    push @{"JSON::XS::Boolean::ISA"}, qw(JSON::PP::Boolean);
-    push @{"JSON::PP::Boolean::ISA"}, qw(JSON::Boolean);
-
-    $JSON::DEBUG and Carp::carp("set -support_by_pp mode.");
-
-    return 1;
-}
-
-
-
-
-#
-# Helper classes for XS
-#
-
-package JSON::Backend::XS::Supportable;
-
-$Carp::Internal{'JSON::Backend::XS::Supportable'} = 1;
-
-sub _make_unsupported_method {
-    my ($pkg, $method, $type) = @_;
-
-    local $^W;
-    no strict qw(refs);
-
-    *{"$pkg\::$method"} = sub {
-        local $^W;
-        if (defined $_[1] ? $_[1] : 1) {
-            ${$_[0]} |= $type;
-        }
-        else {
-            ${$_[0]} &= ~$type;
-        }
-        $_[0];
-    };
-
-    *{"$pkg\::get_$method"} = sub {
-        ${$_[0]} & $type ? 1 : '';
-    };
-
-}
-
-
-sub _set_for_pp {
-    require JSON::PP;
-    my $type  = shift;
-    my $pp    = new JSON::PP;
-    my $prop = $_[0]->property;
-
-    for my $name (keys %$prop) {
-        $pp->$name( $prop->{$name} ? $prop->{$name} : 0 );
-    }
-
-    my $unsupported = $type eq 'encode' ? 
JSON::Backend::XS::UNSUPPORTED_ENCODE_FLAG
-                                        : 
JSON::Backend::XS::UNSUPPORTED_DECODE_FLAG;
-    my $flags       = ${$_[0]} || 0;
-
-    for my $name (keys %$unsupported) {
-        next if ($name eq 'EXPANDED'); # for developer's
-        my $enable = ($flags & $unsupported->{$name}) ? 1 : 0;
-        my $method = lc $name;
-        $pp->$method($enable);
-    }
-
-    $pp->indent_length( $_[0]->get_indent_length );
-
-    return $pp;
-}
-
-sub _encode { # using with PP encod
-    if (${$_[0]}) {
-        _set_for_pp('encode' => @_)->encode($_[1]);
-    }
-    else {
-        $_[0]->_original_encode( $_[1] );
-    }
-}
-
-
-sub _decode { # if unsupported-flag is set, use PP
-    if (${$_[0]}) {
-        _set_for_pp('decode' => @_)->decode($_[1]);
-    }
-    else {
-        $_[0]->_original_decode( $_[1] );
-    }
-}
-
-
-sub decode_prefix { # if unsupported-flag is set, use PP
-    _set_for_pp('decode' => @_)->decode_prefix($_[1]);
-}
-
-
-sub _incr_parse {
-    if (${$_[0]}) {
-        _set_for_pp('decode' => @_)->incr_parse($_[1]);
-    }
-    else {
-        $_[0]->_original_incr_parse( $_[1] );
-    }
-}
-
-
-sub get_indent_length {
-    ${$_[0]} << 4 >> 16;
-}
-
-
-sub indent_length {
-    my $length = $_[1];
-
-    if (!defined $length or $length > 15 or $length < 0) {
-        Carp::carp "The acceptable range of indent_length() is 0 to 15.";
-    }
-    else {
-        local $^W;
-        $length <<= 12;
-        ${$_[0]} &= ~ JSON::Backend::XS::INDENT_LENGTH_FLAG;
-        ${$_[0]} |= $length;
-        *JSON::XS::encode = \&JSON::Backend::XS::Supportable::_encode;
-    }
-
-    $_[0];
-}
-
-
-1;
-__END__
-
-=head1 NAME
-
-JSON - JSON (JavaScript Object Notation) encoder/decoder
-
-=head1 SYNOPSIS
-
- use JSON; # imports encode_json, decode_json, to_json and from_json.
- 
- # simple and fast interfaces (expect/generate UTF-8)
- 
- $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
- $perl_hash_or_arrayref  = decode_json $utf8_encoded_json_text;
- 
- # OO-interface
- 
- $json = JSON->new->allow_nonref;
- 
- $json_text   = $json->encode( $perl_scalar );
- $perl_scalar = $json->decode( $json_text );
- 
- $pretty_printed = $json->pretty->encode( $perl_scalar ); # pretty-printing
- 
- # If you want to use PP only support features, call with '-support_by_pp'
- # When XS unsupported feature is enable, using PP (de|en)code instead of XS 
ones.
- 
- use JSON -support_by_pp;
- 
- # option-acceptable interfaces (expect/generate UNICODE by default)
- 
- $json_text   = to_json( $perl_scalar, { ascii => 1, pretty => 1 } );
- $perl_scalar = from_json( $json_text, { utf8  => 1 } );
- 
- # Between (en|de)code_json and (to|from)_json, if you want to write
- # a code which communicates to an outer world (encoded in UTF-8),
- # recommend to use (en|de)code_json.
- 
-=head1 VERSION
-
-    2.27
-
-This version is compatible with JSON::XS B<2.27> and later.
-
-
-=head1 DESCRIPTION
-
- ************************** CAUTION ********************************
- * This is 'JSON module version 2' and there are many differences  *
- * to version 1.xx                                                 *
- * Please check your applications useing old version.              *
- *   See to 'INCOMPATIBLE CHANGES TO OLD VERSION'                  *
- *******************************************************************
-
-JSON (JavaScript Object Notation) is a simple data format.
-See to L<http://www.json.org/> and 
C<RFC4627>(L<http://www.ietf.org/rfc/rfc4627.txt>).
-
-This module converts Perl data structures to JSON and vice versa using either
-L<JSON::XS> or L<JSON::PP>.
-
-JSON::XS is the fastest and most proper JSON module on CPAN which must be
-compiled and installed in your environment.
-JSON::PP is a pure-Perl module which is bundled in this distribution and
-has a strong compatibility to JSON::XS.
-
-This module try to use JSON::XS by default and fail to it, use JSON::PP 
instead.
-So its features completely depend on JSON::XS or JSON::PP.
-
-See to L<BACKEND MODULE DECISION>.
-
-To distinguish the module name 'JSON' and the format type JSON,
-the former is quoted by CE<lt>E<gt> (its results vary with your using media),
-and the latter is left just as it is.
-
-Module name : C<JSON>
-
-Format type : JSON
-
-=head2 FEATURES
-
-=over
-
-=item * correct unicode handling
-
-This module (i.e. backend modules) knows how to handle Unicode, documents
-how and when it does so, and even documents what "correct" means.
-
-Even though there are limitations, this feature is available since Perl 
version 5.6.
-
-JSON::XS requires Perl 5.8.2 (but works correctly in 5.8.8 or later), so in 
older versions
-C<JSON> sholud call JSON::PP as the backend which can be used since Perl 5.005.
-
-With Perl 5.8.x JSON::PP works, but from 5.8.0 to 5.8.2, because of a Perl 
side problem,
-JSON::PP works slower in the versions. And in 5.005, the Unicode handling is 
not available.
-See to L<JSON::PP/UNICODE HANDLING ON PERLS> for more information.
-
-See also to L<JSON::XS/A FEW NOTES ON UNICODE AND PERL>
-and L<JSON::XS/ENCODING/CODESET_FLAG_NOTES>.
-
-
-=item * round-trip integrity
-
-When you serialise a perl data structure using only data types supported
-by JSON and Perl, the deserialised data structure is identical on the Perl
-level. (e.g. the string "2.0" doesn't suddenly become "2" just because
-it looks like a number). There I<are> minor exceptions to this, read the
-L</MAPPING> section below to learn about those.
-
-
-=item * strict checking of JSON correctness
-
-There is no guessing, no generating of illegal JSON texts by default,
-and only JSON is accepted as input by default (the latter is a security
-feature).
-
-See to L<JSON::XS/FEATURES> and L<JSON::PP/FEATURES>.
-
-=item * fast
-
-This module returns a JSON::XS object itself if available.
-Compared to other JSON modules and other serialisers such as Storable,
-JSON::XS usually compares favourably in terms of speed, too.
-
-If not available, C<JSON> returns a JSON::PP object instead of JSON::XS and
-it is very slow as pure-Perl.
-
-=item * simple to use
-
-This module has both a simple functional interface as well as an
-object oriented interface interface.
-
-=item * reasonably versatile output formats
-
-You can choose between the most compact guaranteed-single-line format possible
-(nice for simple line-based protocols), a pure-ASCII format (for when your 
transport
-is not 8-bit clean, still supports the whole Unicode range), or a 
pretty-printed
-format (for when you want to read that stuff). Or you can combine those 
features
-in whatever way you like.
-
-=back
-
-=head1 FUNCTIONAL INTERFACE
-
-Some documents are copied and modified from L<JSON::XS/FUNCTIONAL INTERFACE>.
-C<to_json> and C<from_json> are additional functions.
-
-=head2 encode_json
-
-    $json_text = encode_json $perl_scalar
-
-Converts the given Perl data structure to a UTF-8 encoded, binary string.
-
-This function call is functionally identical to:
-
-    $json_text = JSON->new->utf8->encode($perl_scalar)
-
-=head2 decode_json
-
-    $perl_scalar = decode_json $json_text
-
-The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
-to parse that as an UTF-8 encoded JSON text, returning the resulting
-reference.
-
-This function call is functionally identical to:
-
-    $perl_scalar = JSON->new->utf8->decode($json_text)
-
-
-=head2 to_json
-
-   $json_text = to_json($perl_scalar)
-
-Converts the given Perl data structure to a json string.
-
-This function call is functionally identical to:
-
-   $json_text = JSON->new->encode($perl_scalar)
-
-Takes a hash reference as the second.
-
-   $json_text = to_json($perl_scalar, $flag_hashref)
-
-So,
-
-   $json_text = encode_json($perl_scalar, {utf8 => 1, pretty => 1})
-
-equivalent to:
-
-   $json_text = JSON->new->utf8(1)->pretty(1)->encode($perl_scalar)
-
-If you want to write a modern perl code which communicates to outer world,
-you should use C<encode_json> (supposed that JSON data are encoded in UTF-8).
-
-=head2 from_json
-
-   $perl_scalar = from_json($json_text)
-
-The opposite of C<to_json>: expects a json string and tries
-to parse it, returning the resulting reference.
-
-This function call is functionally identical to:
-
-    $perl_scalar = JSON->decode($json_text)
-
-Takes a hash reference as the second.
-
-    $perl_scalar = from_json($json_text, $flag_hashref)
-
-So,
-
-    $perl_scalar = from_json($json_text, {utf8 => 1})
-
-equivalent to:
-
-    $perl_scalar = JSON->new->utf8(1)->decode($json_text)
-
-If you want to write a modern perl code which communicates to outer world,
-you should use C<decode_json> (supposed that JSON data are encoded in UTF-8).
-
-=head2 JSON::is_bool
-
-    $is_boolean = JSON::is_bool($scalar)
-
-Returns true if the passed scalar represents either JSON::true or
-JSON::false, two constants that act like C<1> and C<0> respectively
-and are also used to represent JSON C<true> and C<false> in Perl strings.
-
-=head2 JSON::true
-
-Returns JSON true value which is blessed object.
-It C<isa> JSON::Boolean object.
-
-=head2 JSON::false
-
-Returns JSON false value which is blessed object.
-It C<isa> JSON::Boolean object.
-
-=head2 JSON::null
-
-Returns C<undef>.
-
-See L<MAPPING>, below, for more information on how JSON values are mapped to
-Perl.
-
-=head1 HOW DO I DECODE A DATA FROM OUTER AND ENCODE TO OUTER
-
-This section supposes that your perl vresion is 5.8 or later.
-
-If you know a JSON text from an outer world - a network, a file content, and 
so on,
-is encoded in UTF-8, you should use C<decode_json> or C<JSON> module object
-with C<utf8> enable. And the decoded result will contain UNICODE characters.
-
-  # from network
-  my $json        = JSON->new->utf8;
-  my $json_text   = CGI->new->param( 'json_data' );
-  my $perl_scalar = $json->decode( $json_text );
-  
-  # from file content
-  local $/;
-  open( my $fh, '<', 'json.data' );
-  $json_text   = <$fh>;
-  $perl_scalar = decode_json( $json_text );
-
-If an outer data is not encoded in UTF-8, firstly you should C<decode> it.
-
-  use Encode;
-  local $/;
-  open( my $fh, '<', 'json.data' );
-  my $encoding = 'cp932';
-  my $unicode_json_text = decode( $encoding, <$fh> ); # UNICODE
-  
-  # or you can write the below code.
-  #
-  # open( my $fh, "<:encoding($encoding)", 'json.data' );
-  # $unicode_json_text = <$fh>;
-
-In this case, C<$unicode_json_text> is of course UNICODE string.
-So you B<cannot> use C<decode_json> nor C<JSON> module object with C<utf8> 
enable.
-Instead of them, you use C<JSON> module object with C<utf8> disable or 
C<from_json>.
-
-  $perl_scalar = $json->utf8(0)->decode( $unicode_json_text );
-  # or
-  $perl_scalar = from_json( $unicode_json_text );
-
-Or C<encode 'utf8'> and C<decode_json>:
-
-  $perl_scalar = decode_json( encode( 'utf8', $unicode_json_text ) );
-  # this way is not efficient.
-
-And now, you want to convert your C<$perl_scalar> into JSON data and
-send it to an outer world - a network or a file content, and so on.
-
-Your data usually contains UNICODE strings and you want the converted data to 
be encoded
-in UTF-8, you should use C<encode_json> or C<JSON> module object with C<utf8> 
enable.
-
-  print encode_json( $perl_scalar ); # to a network? file? or display?
-  # or
-  print $json->utf8->encode( $perl_scalar );
-
-If C<$perl_scalar> does not contain UNICODE but C<$encoding>-encoded strings
-for some reason, then its characters are regarded as B<latin1> for perl
-(because it does not concern with your $encoding).
-You B<cannot> use C<encode_json> nor C<JSON> module object with C<utf8> enable.
-Instead of them, you use C<JSON> module object with C<utf8> disable or 
C<to_json>.
-Note that the resulted text is a UNICODE string but no problem to print it.
-
-  # $perl_scalar contains $encoding encoded string values
-  $unicode_json_text = $json->utf8(0)->encode( $perl_scalar );
-  # or 
-  $unicode_json_text = to_json( $perl_scalar );
-  # $unicode_json_text consists of characters less than 0x100
-  print $unicode_json_text;
-
-Or C<decode $encoding> all string values and C<encode_json>:
-
-  $perl_scalar->{ foo } = decode( $encoding, $perl_scalar->{ foo } );
-  # ... do it to each string values, then encode_json
-  $json_text = encode_json( $perl_scalar );
-
-This method is a proper way but probably not efficient.
-
-See to L<Encode>, L<perluniintro>.
-
-
-=head1 COMMON OBJECT-ORIENTED INTERFACE
-
-=head2 new
-
-    $json = new JSON
-
-Returns a new C<JSON> object inherited from either JSON::XS or JSON::PP
-that can be used to de/encode JSON strings.
-
-All boolean flags described below are by default I<disabled>.
-
-The mutators for flags all return the JSON object again and thus calls can
-be chained:
-
-   my $json = JSON->new->utf8->space_after->encode({a => [1,2]})
-   => {"a": [1, 2]}
-
-=head2 ascii
-
-    $json = $json->ascii([$enable])
-    
-    $enabled = $json->get_ascii
-
-If $enable is true (or missing), then the encode method will not generate 
characters outside
-the code range 0..127. Any Unicode characters outside that range will be 
escaped using either
-a single \uXXXX or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.
-
-If $enable is false, then the encode method will not escape Unicode characters 
unless
-required by the JSON syntax or other flags. This results in a faster and more 
compact format.
-
-This feature depends on the used Perl version and environment.
-
-See to L<JSON::PP/UNICODE HANDLING ON PERLS> if the backend is PP.
-
-  JSON->new->ascii(1)->encode([chr 0x10401])
-  => ["\ud801\udc01"]
-
-=head2 latin1
-
-    $json = $json->latin1([$enable])
-    
-    $enabled = $json->get_latin1
-
-If $enable is true (or missing), then the encode method will encode the 
resulting JSON
-text as latin1 (or iso-8859-1), escaping any characters outside the code range 
0..255.
-
-If $enable is false, then the encode method will not escape Unicode characters
-unless required by the JSON syntax or other flags.
-
-  JSON->new->latin1->encode (["\x{89}\x{abc}"]
-  => ["\x{89}\\u0abc"]    # (perl syntax, U+abc escaped, U+89 not)
-
-=head2 utf8
-
-    $json = $json->utf8([$enable])
-    
-    $enabled = $json->get_utf8
-
-If $enable is true (or missing), then the encode method will encode the JSON 
result
-into UTF-8, as required by many protocols, while the decode method expects to 
be handled
-an UTF-8-encoded string. Please note that UTF-8-encoded strings do not contain 
any
-characters outside the range 0..255, they are thus useful for bytewise/binary 
I/O.
-
-In future versions, enabling this option might enable autodetection of the 
UTF-16 and UTF-32
-encoding families, as described in RFC4627.
-
-If $enable is false, then the encode method will return the JSON string as a 
(non-encoded)
-Unicode string, while decode expects thus a Unicode string. Any decoding or 
encoding
-(e.g. to UTF-8 or UTF-16) needs to be done yourself, e.g. using the Encode 
module.
-
-
-Example, output UTF-16BE-encoded JSON:
-
-  use Encode;
-  $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object);
-
-Example, decode UTF-32LE-encoded JSON:
-
-  use Encode;
-  $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
-
-See to L<JSON::PP/UNICODE HANDLING ON PERLS> if the backend is PP.
-
-
-=head2 pretty
-
-    $json = $json->pretty([$enable])
-
-This enables (or disables) all of the C<indent>, C<space_before> and
-C<space_after> (and in the future possibly more) flags in one call to
-generate the most readable (or most compact) form possible.
-
-Equivalent to:
-
-   $json->indent->space_before->space_after
-
-The indent space length is three and JSON::XS cannot change the indent
-space length.
-
-=head2 indent
-
-    $json = $json->indent([$enable])
-    
-    $enabled = $json->get_indent
-
-If C<$enable> is true (or missing), then the C<encode> method will use a 
multiline
-format as output, putting every array member or object/hash key-value pair
-into its own line, identing them properly.
-
-If C<$enable> is false, no newlines or indenting will be produced, and the
-resulting JSON text is guarenteed not to contain any C<newlines>.
-
-This setting has no effect when decoding JSON texts.
-
-The indent space length is three.
-With JSON::PP, you can also access C<indent_length> to change indent space 
length.
-
-
-=head2 space_before
-
-    $json = $json->space_before([$enable])
-    
-    $enabled = $json->get_space_before
-
-If C<$enable> is true (or missing), then the C<encode> method will add an extra
-optional space before the C<:> separating keys from values in JSON objects.
-
-If C<$enable> is false, then the C<encode> method will not add any extra
-space at those places.
-
-This setting has no effect when decoding JSON texts.
-
-Example, space_before enabled, space_after and indent disabled:
-
-   {"key" :"value"}
-
-
-=head2 space_after
-
-    $json = $json->space_after([$enable])
-    
-    $enabled = $json->get_space_after
-
-If C<$enable> is true (or missing), then the C<encode> method will add an extra
-optional space after the C<:> separating keys from values in JSON objects
-and extra whitespace after the C<,> separating key-value pairs and array
-members.
-
-If C<$enable> is false, then the C<encode> method will not add any extra
-space at those places.
-
-This setting has no effect when decoding JSON texts.
-
-Example, space_before and indent disabled, space_after enabled:
-
-   {"key": "value"}
-
-
-=head2 relaxed
-
-    $json = $json->relaxed([$enable])
-    
-    $enabled = $json->get_relaxed
-
-If C<$enable> is true (or missing), then C<decode> will accept some
-extensions to normal JSON syntax (see below). C<encode> will not be
-affected in anyway. I<Be aware that this option makes you accept invalid
-JSON texts as if they were valid!>. I suggest only to use this option to
-parse application-specific files written by humans (configuration files,
-resource files etc.)
-
-If C<$enable> is false (the default), then C<decode> will only accept
-valid JSON texts.
-
-Currently accepted extensions are:
-
-=over 4
-
-=item * list items can have an end-comma
-
-JSON I<separates> array elements and key-value pairs with commas. This
-can be annoying if you write JSON texts manually and want to be able to
-quickly append elements, so this extension accepts comma at the end of
-such items not just between them:
-
-   [
-      1,
-      2, <- this comma not normally allowed
-   ]
-   {
-      "k1": "v1",
-      "k2": "v2", <- this comma not normally allowed
-   }
-
-=item * shell-style '#'-comments
-
-Whenever JSON allows whitespace, shell-style comments are additionally
-allowed. They are terminated by the first carriage-return or line-feed
-character, after which more white-space and comments are allowed.
-
-  [
-     1, # this comment not allowed in JSON
-        # neither this one...
-  ]
-
-=back
-
-
-=head2 canonical
-
-    $json = $json->canonical([$enable])
-    
-    $enabled = $json->get_canonical
-
-If C<$enable> is true (or missing), then the C<encode> method will output JSON 
objects
-by sorting their keys. This is adding a comparatively high overhead.
-
-If C<$enable> is false, then the C<encode> method will output key-value
-pairs in the order Perl stores them (which will likely change between runs
-of the same script).
-
-This option is useful if you want the same data structure to be encoded as
-the same JSON text (given the same overall settings). If it is disabled,
-the same hash might be encoded differently even if contains the same data,
-as key-value pairs have no inherent ordering in Perl.
-
-This setting has no effect when decoding JSON texts.
-
-=head2 allow_nonref
-
-    $json = $json->allow_nonref([$enable])
-    
-    $enabled = $json->get_allow_nonref
-
-If C<$enable> is true (or missing), then the C<encode> method can convert a
-non-reference into its corresponding string, number or null JSON value,
-which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
-values instead of croaking.
-
-If C<$enable> is false, then the C<encode> method will croak if it isn't
-passed an arrayref or hashref, as JSON texts must either be an object
-or array. Likewise, C<decode> will croak if given something that is not a
-JSON object or array.
-
-   JSON->new->allow_nonref->encode ("Hello, World!")
-   => "Hello, World!"
-
-=head2 allow_unknown
-
-    $json = $json->allow_unknown ([$enable])
-    
-    $enabled = $json->get_allow_unknown
-
-If $enable is true (or missing), then "encode" will *not* throw an
-exception when it encounters values it cannot represent in JSON (for
-example, filehandles) but instead will encode a JSON "null" value.
-Note that blessed objects are not included here and are handled
-separately by c<allow_nonref>.
-
-If $enable is false (the default), then "encode" will throw an
-exception when it encounters anything it cannot encode as JSON.
-
-This option does not affect "decode" in any way, and it is
-recommended to leave it off unless you know your communications
-partner.
-
-=head2 allow_blessed
-
-    $json = $json->allow_blessed([$enable])
-    
-    $enabled = $json->get_allow_blessed
-
-If C<$enable> is true (or missing), then the C<encode> method will not
-barf when it encounters a blessed reference. Instead, the value of the
-B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
-disabled or no C<TO_JSON> method found) or a representation of the
-object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
-encoded. Has no effect on C<decode>.
-
-If C<$enable> is false (the default), then C<encode> will throw an
-exception when it encounters a blessed object.
-
-
-=head2 convert_blessed
-
-    $json = $json->convert_blessed([$enable])
-    
-    $enabled = $json->get_convert_blessed
-
-If C<$enable> is true (or missing), then C<encode>, upon encountering a
-blessed object, will check for the availability of the C<TO_JSON> method
-on the object's class. If found, it will be called in scalar context
-and the resulting scalar will be encoded instead of the object. If no
-C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
-to do.
-
-The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
-returns other blessed objects, those will be handled in the same
-way. C<TO_JSON> must take care of not causing an endless recursion cycle
-(== crash) in this case. The name of C<TO_JSON> was chosen because other
-methods called by the Perl core (== not by the user of the object) are
-usually in upper case letters and to avoid collisions with the C<to_json>
-function or method.
-
-This setting does not yet influence C<decode> in any way.
-
-If C<$enable> is false, then the C<allow_blessed> setting will decide what
-to do when a blessed object is found.
-
-=over
-
-=item convert_blessed_universally mode
-
-If use C<JSON> with C<-convert_blessed_universally>, the C<UNIVERSAL::TO_JSON>
-subroutine is defined as the below code:
-
-   *UNIVERSAL::TO_JSON = sub {
-       my $b_obj = B::svref_2object( $_[0] );
-       return    $b_obj->isa('B::HV') ? { %{ $_[0] } }
-               : $b_obj->isa('B::AV') ? [ @{ $_[0] } ]
-               : undef
-               ;
-   }
-
-This will cause that C<encode> method converts simple blessed objects into
-JSON objects as non-blessed object.
-
-   JSON -convert_blessed_universally;
-   $json->allow_blessed->convert_blessed->encode( $blessed_object )
-
-This feature is experimental and may be removed in the future.
-
-=back
-
-=head2 filter_json_object
-
-    $json = $json->filter_json_object([$coderef])
-
-When C<$coderef> is specified, it will be called from C<decode> each
-time it decodes a JSON object. The only argument passed to the coderef
-is a reference to the newly-created hash. If the code references returns
-a single scalar (which need not be a reference), this value
-(i.e. a copy of that scalar to avoid aliasing) is inserted into the
-deserialised data structure. If it returns an empty list
-(NOTE: I<not> C<undef>, which is a valid scalar), the original deserialised
-hash will be inserted. This setting can slow down decoding considerably.
-
-When C<$coderef> is omitted or undefined, any existing callback will
-be removed and C<decode> will not change the deserialised hash in any
-way.
-
-Example, convert all JSON objects into the integer 5:
-
-   my $js = JSON->new->filter_json_object (sub { 5 });
-   # returns [5]
-   $js->decode ('[{}]'); # the given subroutine takes a hash reference.
-   # throw an exception because allow_nonref is not enabled
-   # so a lone 5 is not allowed.
-   $js->decode ('{"a":1, "b":2}');
-
-
-=head2 filter_json_single_key_object
-
-    $json = $json->filter_json_single_key_object($key [=> $coderef])
-
-Works remotely similar to C<filter_json_object>, but is only called for
-JSON objects having a single key named C<$key>.
-
-This C<$coderef> is called before the one specified via
-C<filter_json_object>, if any. It gets passed the single value in the JSON
-object. If it returns a single value, it will be inserted into the data
-structure. If it returns nothing (not even C<undef> but the empty list),
-the callback from C<filter_json_object> will be called next, as if no
-single-key callback were specified.
-
-If C<$coderef> is omitted or undefined, the corresponding callback will be
-disabled. There can only ever be one callback for a given key.
-
-As this callback gets called less often then the C<filter_json_object>
-one, decoding speed will not usually suffer as much. Therefore, single-key
-objects make excellent targets to serialise Perl objects into, especially
-as single-key JSON objects are as close to the type-tagged value concept
-as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
-support this in any way, so you need to make sure your data never looks
-like a serialised Perl hash.
-
-Typical names for the single object key are C<__class_whatever__>, or
-C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
-things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
-with real hashes.
-
-Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
-into the corresponding C<< $WIDGET{<id>} >> object:
-
-   # return whatever is in $WIDGET{5}:
-   JSON
-      ->new
-      ->filter_json_single_key_object (__widget__ => sub {
-            $WIDGET{ $_[0] }
-         })
-      ->decode ('{"__widget__": 5')
-
-   # this can be used with a TO_JSON method in some "widget" class
-   # for serialisation to json:
-   sub WidgetBase::TO_JSON {
-      my ($self) = @_;
-
-      unless ($self->{id}) {
-         $self->{id} = ..get..some..id..;
-         $WIDGET{$self->{id}} = $self;
-      }
-
-      { __widget__ => $self->{id} }
-   }
-
-
-=head2 shrink
-
-    $json = $json->shrink([$enable])
-    
-    $enabled = $json->get_shrink
-
-With JSON::XS, this flag resizes strings generated by either
-C<encode> or C<decode> to their minimum size possible. This can save
-memory when your JSON texts are either very very long or you have many
-short strings. It will also try to downgrade any strings to octet-form
-if possible: perl stores strings internally either in an encoding called
-UTF-X or in octet-form. The latter cannot store everything but uses less
-space in general (and some buggy Perl or C code might even rely on that
-internal representation being used).
-
-With JSON::PP, it is noop about resizing strings but tries
-C<utf8::downgrade> to the returned string by C<encode>. See to L<utf8>.
-
-See to L<JSON::XS/OBJECT-ORIENTED INTERFACE> and L<JSON::PP/METHODS>.
-
-=head2 max_depth
-
-    $json = $json->max_depth([$maximum_nesting_depth])
-    
-    $max_depth = $json->get_max_depth
-
-Sets the maximum nesting level (default C<512>) accepted while encoding
-or decoding. If a higher nesting level is detected in JSON text or a Perl
-data structure, then the encoder and decoder will stop and croak at that
-point.
-
-Nesting level is defined by number of hash- or arrayrefs that the encoder
-needs to traverse to reach a given point or the number of C<{> or C<[>
-characters without their matching closing parenthesis crossed to reach a
-given character in a string.
-
-If no argument is given, the highest possible setting will be used, which
-is rarely useful.
-
-Note that nesting is implemented by recursion in C. The default value has
-been chosen to be as large as typical operating systems allow without
-crashing. (JSON::XS)
-
-With JSON::PP as the backend, when a large value (100 or more) was set and
-it de/encodes a deep nested object/text, it may raise a warning
-'Deep recursion on subroutin' at the perl runtime phase.
-
-See L<JSON::XS/SECURITY CONSIDERATIONS> for more info on why this is useful.
-
-=head2 max_size
-
-    $json = $json->max_size([$maximum_string_size])
-    
-    $max_size = $json->get_max_size
-
-Set the maximum length a JSON text may have (in bytes) where decoding is
-being attempted. The default is C<0>, meaning no limit. When C<decode>
-is called on a string that is longer then this many bytes, it will not
-attempt to decode the string but throw an exception. This setting has no
-effect on C<encode> (yet).
-
-If no argument is given, the limit check will be deactivated (same as when
-C<0> is specified).
-
-See L<JSON::XS/SECURITY CONSIDERATIONS>, below, for more info on why this is 
useful.
-
-=head2 encode
-
-    $json_text = $json->encode($perl_scalar)
-
-Converts the given Perl data structure (a simple scalar or a reference
-to a hash or array) to its JSON representation. Simple scalars will be
-converted into JSON string or number sequences, while references to arrays
-become JSON arrays and references to hashes become JSON objects. Undefined
-Perl values (e.g. C<undef>) become JSON C<null> values.
-References to the integers C<0> and C<1> are converted into C<true> and 
C<false>.
-
-=head2 decode
-
-    $perl_scalar = $json->decode($json_text)
-
-The opposite of C<encode>: expects a JSON text and tries to parse it,
-returning the resulting simple scalar or reference. Croaks on error.
-
-JSON numbers and strings become simple Perl scalars. JSON arrays become
-Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
-C<1> (C<JSON::true>), C<false> becomes C<0> (C<JSON::false>) and
-C<null> becomes C<undef>.
-
-=head2 decode_prefix
-
-    ($perl_scalar, $characters) = $json->decode_prefix($json_text)
-
-This works like the C<decode> method, but instead of raising an exception
-when there is trailing garbage after the first JSON object, it will
-silently stop parsing there and return the number of characters consumed
-so far.
-
-   JSON->new->decode_prefix ("[1] the tail")
-   => ([], 3)
-
-See to L<JSON::XS/OBJECT-ORIENTED INTERFACE>
-
-=head2 property
-
-    $boolean = $json->property($property_name)
-
-Returns a boolean value about above some properties.
-
-The available properties are C<ascii>, C<latin1>, C<utf8>,
-C<indent>,C<space_before>, C<space_after>, C<relaxed>, C<canonical>,
-C<allow_nonref>, C<allow_unknown>, C<allow_blessed>, C<convert_blessed>,
-C<shrink>, C<max_depth> and C<max_size>.
-
-   $boolean = $json->property('utf8');
-    => 0
-   $json->utf8;
-   $boolean = $json->property('utf8');
-    => 1
-
-Sets the property with a given boolean value.
-
-    $json = $json->property($property_name => $boolean);
-
-With no argumnt, it returns all the above properties as a hash reference.
-
-    $flag_hashref = $json->property();
-
-=head1 INCREMENTAL PARSING
-
-Most of this section are copied and modified from L<JSON::XS/INCREMENTAL 
PARSING>.
-
-In some cases, there is the need for incremental parsing of JSON texts.
-This module does allow you to parse a JSON stream incrementally.
-It does so by accumulating text until it has a full JSON object, which
-it then can decode. This process is similar to using C<decode_prefix>
-to see if a full JSON object is available, but is much more efficient
-(and can be implemented with a minimum of method calls).
-
-The backend module will only attempt to parse the JSON text once it is sure it
-has enough text to get a decisive result, using a very simple but
-truly incremental parser. This means that it sometimes won't stop as
-early as the full parser, for example, it doesn't detect parenthese
-mismatches. The only thing it guarantees is that it starts decoding as
-soon as a syntactically valid JSON text has been seen. This means you need
-to set resource limits (e.g. C<max_size>) to ensure the parser will stop
-parsing in the presence if syntax errors.
-
-The following methods implement this incremental parser.
-
-=head2 incr_parse
-
-    $json->incr_parse( [$string] ) # void context
-    
-    $obj_or_undef = $json->incr_parse( [$string] ) # scalar context
-    
-    @obj_or_empty = $json->incr_parse( [$string] ) # list context
-
-This is the central parsing function. It can both append new text and
-extract objects from the stream accumulated so far (both of these
-functions are optional).
-
-If C<$string> is given, then this string is appended to the already
-existing JSON fragment stored in the C<$json> object.
-
-After that, if the function is called in void context, it will simply
-return without doing anything further. This can be used to add more text
-in as many chunks as you want.
-
-If the method is called in scalar context, then it will try to extract
-exactly I<one> JSON object. If that is successful, it will return this
-object, otherwise it will return C<undef>. If there is a parse error,
-this method will croak just as C<decode> would do (one can then use
-C<incr_skip> to skip the errornous part). This is the most common way of
-using the method.
-
-And finally, in list context, it will try to extract as many objects
-from the stream as it can find and return them, or the empty list
-otherwise. For this to work, there must be no separators between the JSON
-objects or arrays, instead they must be concatenated back-to-back. If
-an error occurs, an exception will be raised as in the scalar context
-case. Note that in this case, any previously-parsed JSON texts will be
-lost.
-
-Example: Parse some JSON arrays/objects in a given string and return them.
-
-    my @objs = JSON->new->incr_parse ("[5][7][1,2]");
-
-=head2 incr_text
-
-    $lvalue_string = $json->incr_text
-
-This method returns the currently stored JSON fragment as an lvalue, that
-is, you can manipulate it. This I<only> works when a preceding call to
-C<incr_parse> in I<scalar context> successfully returned an object. Under
-all other circumstances you must not call this function (I mean it.
-although in simple tests it might actually work, it I<will> fail under
-real world conditions). As a special exception, you can also call this
-method before having parsed anything.
-
-This function is useful in two cases: a) finding the trailing text after a
-JSON object or b) parsing multiple JSON objects separated by non-JSON text
-(such as commas).
-
-    $json->incr_text =~ s/\s*,\s*//;
-
-In Perl 5.005, C<lvalue> attribute is not available.
-You must write codes like the below:
-
-    $string = $json->incr_text;
-    $string =~ s/\s*,\s*//;
-    $json->incr_text( $string );
-
-=head2 incr_skip
-
-    $json->incr_skip
-
-This will reset the state of the incremental parser and will remove the
-parsed text from the input buffer. This is useful after C<incr_parse>
-died, in which case the input buffer and incremental parser state is left
-unchanged, to skip the text parsed so far and to reset the parse state.
-
-=head2 incr_reset
-
-    $json->incr_reset
-
-This completely resets the incremental parser, that is, after this call,
-it will be as if the parser had never parsed anything.
-
-This is useful if you want ot repeatedly parse JSON objects and want to
-ignore any trailing data, which means you have to reset the parser after
-each successful decode.
-
-See to L<JSON::XS/INCREMENTAL PARSING> for examples.
-
-
-=head1 JSON::PP SUPPORT METHODS
-
-The below methods are JSON::PP own methods, so when C<JSON> works
-with JSON::PP (i.e. the created object is a JSON::PP object), available.
-See to L<JSON::PP/JSON::PP OWN METHODS> in detail.
-
-If you use C<JSON> with additonal C<-support_by_pp>, some methods
-are available even with JSON::XS. See to L<USE PP FEATURES EVEN THOUGH XS 
BACKEND>.
-
-   BEING { $ENV{PERL_JSON_BACKEND} = 'JSON::XS' }
-   
-   use JSON -support_by_pp;
-   
-   my $json = new JSON;
-   $json->allow_nonref->escape_slash->encode("/");
-
-   # functional interfaces too.
-   print to_json(["/"], {escape_slash => 1});
-   print from_json('["foo"]', {utf8 => 1});
-
-If you do not want to all functions but C<-support_by_pp>,
-use C<-no_export>.
-
-   use JSON -support_by_pp, -no_export;
-   # functional interfaces are not exported.
-
-=head2 allow_singlequote
-
-    $json = $json->allow_singlequote([$enable])
-
-If C<$enable> is true (or missing), then C<decode> will accept
-any JSON strings quoted by single quotations that are invalid JSON
-format.
-
-    $json->allow_singlequote->decode({"foo":'bar'});
-    $json->allow_singlequote->decode({'foo':"bar"});
-    $json->allow_singlequote->decode({'foo':'bar'});
-
-As same as the C<relaxed> option, this option may be used to parse
-application-specific files written by humans.
-
-=head2 allow_barekey
-
-    $json = $json->allow_barekey([$enable])
-
-If C<$enable> is true (or missing), then C<decode> will accept
-bare keys of JSON object that are invalid JSON format.
-
-As same as the C<relaxed> option, this option may be used to parse
-application-specific files written by humans.
-
-    $json->allow_barekey->decode('{foo:"bar"}');
-
-=head2 allow_bignum
-
-    $json = $json->allow_bignum([$enable])
-
-If C<$enable> is true (or missing), then C<decode> will convert
-the big integer Perl cannot handle as integer into a L<Math::BigInt>
-object and convert a floating number (any) into a L<Math::BigFloat>.
-
-On the contary, C<encode> converts C<Math::BigInt> objects and 
C<Math::BigFloat>
-objects into JSON numbers with C<allow_blessed> enable.
-
-   $json->allow_nonref->allow_blessed->allow_bignum;
-   $bigfloat = $json->decode('2.000000000000000000000000001');
-   print $json->encode($bigfloat);
-   # => 2.000000000000000000000000001
-
-See to L<MAPPING> aboout the conversion of JSON number.
-
-=head2 loose
-
-    $json = $json->loose([$enable])
-
-The unescaped [\x00-\x1f\x22\x2f\x5c] strings are invalid in JSON strings
-and the module doesn't allow to C<decode> to these (except for \x2f).
-If C<$enable> is true (or missing), then C<decode>  will accept these
-unescaped strings.
-
-    $json->loose->decode(qq|["abc
-                                   def"]|);
-
-See to L<JSON::PP/JSON::PP OWN METHODS>.
-
-=head2 escape_slash
-
-    $json = $json->escape_slash([$enable])
-
-According to JSON Grammar, I<slash> (U+002F) is escaped. But by default
-JSON backend modules encode strings without escaping slash.
-
-If C<$enable> is true (or missing), then C<encode> will escape slashes.
-
-=head2 indent_length
-
-    $json = $json->indent_length($length)
-
-With JSON::XS, The indent space length is 3 and cannot be changed.
-With JSON::PP, it sets the indent space length with the given $length.
-The default is 3. The acceptable range is 0 to 15.
-
-=head2 sort_by
-
-    $json = $json->sort_by($function_name)
-    $json = $json->sort_by($subroutine_ref)
-
-If $function_name or $subroutine_ref are set, its sort routine are used.
-
-   $js = $pc->sort_by(sub { $JSON::PP::a cmp $JSON::PP::b })->encode($obj);
-   # is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);
-
-   $js = $pc->sort_by('own_sort')->encode($obj);
-   # is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);
-
-   sub JSON::PP::own_sort { $JSON::PP::a cmp $JSON::PP::b }
-
-As the sorting routine runs in the JSON::PP scope, the given
-subroutine name and the special variables C<$a>, C<$b> will begin
-with 'JSON::PP::'.
-
-If $integer is set, then the effect is same as C<canonical> on.
-
-See to L<JSON::PP/JSON::PP OWN METHODS>.
-
-=head1 MAPPING
-
-This section is copied from JSON::XS and modified to C<JSON>.
-JSON::XS and JSON::PP mapping mechanisms are almost equivalent.
-
-See to L<JSON::XS/MAPPING>.
-
-=head2 JSON -> PERL
-
-=over 4
-
-=item object
-
-A JSON object becomes a reference to a hash in Perl. No ordering of object
-keys is preserved (JSON does not preserver object key ordering itself).
-
-=item array
-
-A JSON array becomes a reference to an array in Perl.
-
-=item string
-
-A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON
-are represented by the same codepoints in the Perl string, so no manual
-decoding is necessary.
-
-=item number
-
-A JSON number becomes either an integer, numeric (floating point) or
-string scalar in perl, depending on its range and any fractional parts. On
-the Perl level, there is no difference between those as Perl handles all
-the conversion details, but an integer may take slightly less memory and
-might represent more values exactly than floating point numbers.
-
-If the number consists of digits only, C<JSON> will try to represent
-it as an integer value. If that fails, it will try to represent it as
-a numeric (floating point) value if that is possible without loss of
-precision. Otherwise it will preserve the number as a string value (in
-which case you lose roundtripping ability, as the JSON number will be
-re-encoded toa JSON string).
-
-Numbers containing a fractional or exponential part will always be
-represented as numeric (floating point) values, possibly at a loss of
-precision (in which case you might lose perfect roundtripping ability, but
-the JSON number will still be re-encoded as a JSON number).
-
-Note that precision is not accuracy - binary floating point values cannot
-represent most decimal fractions exactly, and when converting from and to
-floating point, C<JSON> only guarantees precision up to but not including
-the leats significant bit.
-
-If the backend is JSON::PP and C<allow_bignum> is enable, the big integers 
-and the numeric can be optionally converted into L<Math::BigInt> and
-L<Math::BigFloat> objects.
-
-=item true, false
-
-These JSON atoms become C<JSON::true> and C<JSON::false>,
-respectively. They are overloaded to act almost exactly like the numbers
-C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
-the C<JSON::is_bool> function.
-
-If C<JSON::true> and C<JSON::false> are used as strings or compared as strings,
-they represent as C<true> and C<false> respectively.
-
-   print JSON::true . "\n";
-    => true
-   print JSON::true + 1;
-    => 1
-
-   ok(JSON::true eq 'true');
-   ok(JSON::true eq  '1');
-   ok(JSON::true == 1);
-
-C<JSON> will install these missing overloading features to the backend modules.
-
-
-=item null
-
-A JSON null atom becomes C<undef> in Perl.
-
-C<JSON::null> returns C<unddef>.
-
-=back
-
-
-=head2 PERL -> JSON
-
-The mapping from Perl to JSON is slightly more difficult, as Perl is a
-truly typeless language, so we can only guess which JSON type is meant by
-a Perl value.
-
-=over 4
-
-=item hash references
-
-Perl hash references become JSON objects. As there is no inherent ordering
-in hash keys (or JSON objects), they will usually be encoded in a
-pseudo-random order that can change between runs of the same program but
-stays generally the same within a single run of a program. C<JSON>
-optionally sort the hash keys (determined by the I<canonical> flag), so
-the same datastructure will serialise to the same JSON text (given same
-settings and version of JSON::XS), but this incurs a runtime overhead
-and is only rarely useful, e.g. when you want to compare some JSON text
-against another for equality.
-
-In future, the ordered object feature will be added to JSON::PP using C<tie> 
mechanism.
-
-
-=item array references
-
-Perl array references become JSON arrays.
-
-=item other references
-
-Other unblessed references are generally not allowed and will cause an
-exception to be thrown, except for references to the integers C<0> and
-C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
-also use C<JSON::false> and C<JSON::true> to improve readability.
-
-   to_json [\0,JSON::true]      # yields [false,true]
-
-=item JSON::true, JSON::false, JSON::null
-
-These special values become JSON true and JSON false values,
-respectively. You can also use C<\1> and C<\0> directly if you want.
-
-JSON::null returns C<undef>.
-
-=item blessed objects
-
-Blessed objects are not directly representable in JSON. See the
-C<allow_blessed> and C<convert_blessed> methods on various options on
-how to deal with this: basically, you can choose between throwing an
-exception, encoding the reference as if it weren't blessed, or provide
-your own serialiser method.
-
-With C<convert_blessed_universally> mode,  C<encode> converts blessed
-hash references or blessed array references (contains other blessed references)
-into JSON members and arrays.
-
-   use JSON -convert_blessed_universally;
-   JSON->new->allow_blessed->convert_blessed->encode( $blessed_object );
-
-See to L<convert_blessed>.
-
-=item simple scalars
-
-Simple Perl scalars (any scalar that is not a reference) are the most
-difficult objects to encode: JSON::XS and JSON::PP will encode undefined 
scalars as
-JSON C<null> values, scalars that have last been used in a string context
-before encoding as JSON strings, and anything else as number value:
-
-   # dump as number
-   encode_json [2]                      # yields [2]
-   encode_json [-3.0e17]                # yields [-3e+17]
-   my $value = 5; encode_json [$value]  # yields [5]
-
-   # used as string, so dump as string
-   print $value;
-   encode_json [$value]                 # yields ["5"]
-
-   # undef becomes null
-   encode_json [undef]                  # yields [null]
-
-You can force the type to be a string by stringifying it:
-
-   my $x = 3.1; # some variable containing a number
-   "$x";        # stringified
-   $x .= "";    # another, more awkward way to stringify
-   print $x;    # perl does it for you, too, quite often
-
-You can force the type to be a number by numifying it:
-
-   my $x = "3"; # some variable containing a string
-   $x += 0;     # numify it, ensuring it will be dumped as a number
-   $x *= 1;     # same thing, the choise is yours.
-
-You can not currently force the type in other, less obscure, ways.
-
-Note that numerical precision has the same meaning as under Perl (so
-binary to decimal conversion follows the same rules as in Perl, which
-can differ to other languages). Also, your perl interpreter might expose
-extensions to the floating point numbers of your platform, such as
-infinities or NaN's - these cannot be represented in JSON, and it is an
-error to pass those in.
-
-=item Big Number
-
-If the backend is JSON::PP and C<allow_bignum> is enable, 
-C<encode> converts C<Math::BigInt> objects and C<Math::BigFloat>
-objects into JSON numbers.
-
-
-=back
-
-=head1 JSON and ECMAscript
-
-See to L<JSON::XS/JSON and ECMAscript>.
-
-=head1 JSON and YAML
-
-JSON is not a subset of YAML.
-See to L<JSON::XS/JSON and YAML>.
-
-
-=head1 BACKEND MODULE DECISION
-
-When you use C<JSON>, C<JSON> tries to C<use> JSON::XS. If this call failed, 
it will
-C<uses> JSON::PP. The required JSON::XS version is I<2.2> or later.
-
-The C<JSON> constructor method returns an object inherited from the backend 
module,
-and JSON::XS object is a blessed scaler reference while JSON::PP is a blessed 
hash
-reference.
-
-So, your program should not depend on the backend module, especially
-returned objects should not be modified.
-
- my $json = JSON->new; # XS or PP?
- $json->{stash} = 'this is xs object'; # this code may raise an error!
-
-To check the backend module, there are some methods - C<backend>, C<is_pp> and 
C<is_xs>.
-
-  JSON->backend; # 'JSON::XS' or 'JSON::PP'
-  
-  JSON->backend->is_pp: # 0 or 1
-  
-  JSON->backend->is_xs: # 1 or 0
-  
-  $json->is_xs; # 1 or 0
-  
-  $json->is_pp; # 0 or 1
-
-
-If you set an enviornment variable C<PERL_JSON_BACKEND>, The calling action 
will be changed.
-
-=over
-
-=item PERL_JSON_BACKEND = 0 or PERL_JSON_BACKEND = 'JSON::PP'
-
-Always use JSON::PP
-
-=item PERL_JSON_BACKEND == 1 or PERL_JSON_BACKEND = 'JSON::XS,JSON::PP'
-
-(The default) Use compiled JSON::XS if it is properly compiled & installed,
-otherwise use JSON::PP.
-
-=item PERL_JSON_BACKEND == 2 or PERL_JSON_BACKEND = 'JSON::XS'
-
-Always use compiled JSON::XS, die if it isn't properly compiled & installed.
-
-=back
-
-These ideas come from L<DBI::PurePerl> mechanism.
-
-example:
-
- BEGIN { $ENV{PERL_JSON_BACKEND} = 'JSON::PP' }
- use JSON; # always uses JSON::PP
-
-In future, it may be able to specify another module.
-
-=head1 USE PP FEATURES EVEN THOUGH XS BACKEND
-
-Many methods are available with either JSON::XS or JSON::PP and
-when the backend module is JSON::XS, if any JSON::PP specific (i.e. JSON::XS 
unspported)
-method is called, it will C<warn> and be noop.
-
-But If you C<use> C<JSON> passing the optional string C<-support_by_pp>,
-it makes a part of those unupported methods available.
-This feature is achieved by using JSON::PP in C<de/encode>.
-
-   BEGIN { $ENV{PERL_JSON_BACKEND} = 2 } # with JSON::XS
-   use JSON -support_by_pp;
-   my $json = new JSON;
-   $json->allow_nonref->escape_slash->encode("/");
-
-At this time, the returned object is a C<JSON::Backend::XS::Supportable>
-object (re-blessed XS object), and  by checking JSON::XS unsupported flags
-in de/encoding, can support some unsupported methods - C<loose>, 
C<allow_bignum>,
-C<allow_barekey>, C<allow_singlequote>, C<escape_slash> and C<indent_length>.
-
-When any unsupported methods are not enable, C<XS de/encode> will be
-used as is. The switch is achieved by changing the symbolic tables.
-
-C<-support_by_pp> is effective only when the backend module is JSON::XS
-and it makes the de/encoding speed down a bit.
-
-See to L<JSON::PP SUPPORT METHODS>.
-
-=head1 INCOMPATIBLE CHANGES TO OLD VERSION
-
-There are big incompatibility between new version (2.00) and old (1.xx).
-If you use old C<JSON> 1.xx in your code, please check it.
-
-See to L<Transition ways from 1.xx to 2.xx.>
-
-=over
-
-=item jsonToObj and objToJson are obsoleted.
-
-Non Perl-style name C<jsonToObj> and C<objToJson> are obsoleted
-(but not yet deleted from the source).
-If you use these functions in your code, please replace them
-with C<from_json> and C<to_json>.
-
-
-=item Global variables are no longer available.
-
-C<JSON> class variables - C<$JSON::AUTOCONVERT>, C<$JSON::BareKey>, etc...
-- are not available any longer.
-Instead, various features can be used through object methods.
-
-
-=item Package JSON::Converter and JSON::Parser are deleted.
-
-Now C<JSON> bundles with JSON::PP which can handle JSON more properly than 
them.
-
-=item Package JSON::NotString is deleted.
-
-There was C<JSON::NotString> class which represents JSON value C<true>, 
C<false>, C<null>
-and numbers. It was deleted and replaced by C<JSON::Boolean>.
-
-C<JSON::Boolean> represents C<true> and C<false>.
-
-C<JSON::Boolean> does not represent C<null>.
-
-C<JSON::null> returns C<undef>.
-
-C<JSON> makes L<JSON::XS::Boolean> and L<JSON::PP::Boolean> is-a relation
-to L<JSON::Boolean>.
-
-=item function JSON::Number is obsoleted.
-
-C<JSON::Number> is now needless because JSON::XS and JSON::PP have
-round-trip integrity.
-
-=item JSONRPC modules are deleted.
-
-Perl implementation of JSON-RPC protocol - C<JSONRPC >, 
C<JSONRPC::Transport::HTTP>
-and C<Apache::JSONRPC > are deleted in this distribution.
-Instead of them, there is L<JSON::RPC> which supports JSON-RPC protocol 
version 1.1.
-
-=back
-
-=head2 Transition ways from 1.xx to 2.xx.
-
-You should set C<suport_by_pp> mode firstly, because
-it is always successful for the below codes even with JSON::XS.
-
-    use JSON -support_by_pp;
-
-=over
-
-=item Exported jsonToObj (simple)
-
-  from_json($json_text);
-
-=item Exported objToJson (simple)
-
-  to_json($perl_scalar);
-
-=item Exported jsonToObj (advanced)
-
-  $flags = {allow_barekey => 1, allow_singlequote => 1};
-  from_json($json_text, $flags);
-
-equivalent to:
-
-  $JSON::BareKey = 1;
-  $JSON::QuotApos = 1;
-  jsonToObj($json_text);
-
-=item Exported objToJson (advanced)
-
-  $flags = {allow_blessed => 1, allow_barekey => 1};
-  to_json($perl_scalar, $flags);
-
-equivalent to:
-
-  $JSON::BareKey = 1;
-  objToJson($perl_scalar);
-
-=item jsonToObj as object method
-
-  $json->decode($json_text);
-
-=item objToJson as object method
-
-  $json->encode($perl_scalar);
-
-=item new method with parameters
-
-The C<new> method in 2.x takes any parameters no longer.
-You can set parameters instead;
-
-   $json = JSON->new->pretty;
-
-=item $JSON::Pretty, $JSON::Indent, $JSON::Delimiter
-
-If C<indent> is enable, that menas C<$JSON::Pretty> flag set. And
-C<$JSON::Delimiter> was substituted by C<space_before> and C<space_after>.
-In conclusion:
-
-   $json->indent->space_before->space_after;
-
-Equivalent to:
-
-  $json->pretty;
-
-To change indent length, use C<indent_length>.
-
-(Only with JSON::PP, if C<-support_by_pp> is not used.)
-
-  $json->pretty->indent_length(2)->encode($perl_scalar);
-
-=item $JSON::BareKey
-
-(Only with JSON::PP, if C<-support_by_pp> is not used.)
-
-  $json->allow_barekey->decode($json_text)
-
-=item $JSON::ConvBlessed
-
-use C<-convert_blessed_universally>. See to L<convert_blessed>.
-
-=item $JSON::QuotApos
-
-(Only with JSON::PP, if C<-support_by_pp> is not used.)
-
-  $json->allow_singlequote->decode($json_text)
-
-=item $JSON::SingleQuote
-
-Disable. C<JSON> does not make such a invalid JSON string any longer.
-
-=item $JSON::KeySort
-
-  $json->canonical->encode($perl_scalar)
-
-This is the ascii sort.
-
-If you want to use with your own sort routine, check the C<sort_by> method.
-
-(Only with JSON::PP, even if C<-support_by_pp> is used currently.)
-
-  $json->sort_by($sort_routine_ref)->encode($perl_scalar)
- 
-  $json->sort_by(sub { $JSON::PP::a <=> $JSON::PP::b })->encode($perl_scalar)
-
-Can't access C<$a> and C<$b> but C<$JSON::PP::a> and C<$JSON::PP::b>.
-
-=item $JSON::SkipInvalid
-
-  $json->allow_unknown
-
-=item $JSON::AUTOCONVERT
-
-Needless. C<JSON> backend modules have the round-trip integrity.
-
-=item $JSON::UTF8
-
-Needless because C<JSON> (JSON::XS/JSON::PP) sets
-the UTF8 flag on properly.
-
-    # With UTF8-flagged strings
-
-    $json->allow_nonref;
-    $str = chr(1000); # UTF8-flagged
-
-    $json_text  = $json->utf8(0)->encode($str);
-    utf8::is_utf8($json_text);
-    # true
-    $json_text  = $json->utf8(1)->encode($str);
-    utf8::is_utf8($json_text);
-    # false
-
-    $str = '"' . chr(1000) . '"'; # UTF8-flagged
-
-    $perl_scalar  = $json->utf8(0)->decode($str);
-    utf8::is_utf8($perl_scalar);
-    # true
-    $perl_scalar  = $json->utf8(1)->decode($str);
-    # died because of 'Wide character in subroutine'
-
-See to L<JSON::XS/A FEW NOTES ON UNICODE AND PERL>.
-
-=item $JSON::UnMapping
-
-Disable. See to L<MAPPING>.
-
-=item $JSON::SelfConvert
-
-This option was deleted.
-Instead of it, if a givien blessed object has the C<TO_JSON> method,
-C<TO_JSON> will be executed with C<convert_blessed>.
-
-  $json->convert_blessed->encode($bleesed_hashref_or_arrayref)
-  # if need, call allow_blessed
-
-Note that it was C<toJson> in old version, but now not C<toJson> but 
C<TO_JSON>.
-
-=back
-
-=head1 TODO
-
-=over
-
-=item example programs
-
-=back
-
-=head1 THREADS
-
-No test with JSON::PP. If with JSON::XS, See to L<JSON::XS/THREADS>.
-
-
-=head1 BUGS
-
-Please report bugs relevant to C<JSON> to E<lt>makamaka[at]cpan.orgE<gt>.
-
-
-=head1 SEE ALSO
-
-Most of the document is copied and modified from JSON::XS doc.
-
-L<JSON::XS>, L<JSON::PP>
-
-C<RFC4627>(L<http://www.ietf.org/rfc/rfc4627.txt>)
-
-=head1 AUTHOR
-
-Makamaka Hannyaharamitu, E<lt>makamaka[at]cpan.orgE<gt>
-
-JSON::XS was written by  Marc Lehmann <schmorp[at]schmorp.de>
-
-The relese of this new version owes to the courtesy of Marc Lehmann.
-
-
-=head1 COPYRIGHT AND LICENSE
-
-Copyright 2005-2010 by Makamaka Hannyaharamitu
-
-This library is free software; you can redistribute it and/or modify
-it under the same terms as Perl itself. 
-
-=cut
-

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